Machine for producing helicoid surfaces



June 29, 1937. J, FEIRIGUSON 2,085,016

MACHINE FOR PRODUCING HELICOID SURFACES Original Filed April 30, 1932 2 Sheets-Sheet 1 INVENTOR CWv ATTORNEY June 29, 1937a J. FERGUSON MACHINE FOR PRODUCING HELICOID SURFACES 2 SheetsSheet 2 Original Filed April 30, '1932 INVENTOR ATTORNEY Patented June 29 1937 UNITED STATES PATENT OFFICE MACHINE FOR PRODUCING SURFACES John'Ferguson, Hoboken, N. J.

Application April 30, 1932, Serial No. 608,387 Renewed August 29, 1936 4 Claims.

I invention is to provide a method and a means for generating true helicoids on the working surfaces of propeller blades. Still further objects and advantages attaching to the invention and to its use and operation willbe apparent to those skilled in the art from the following particular description and from the appendedv claims.

The invention attains its objects by rotating the propeller about its axis through an arc of a circle, first in one directionand then in. the reverse direction, while moving in a like manner a finishing or grinding tool, in operative relation to the helicoidal surface of one of the blades of said propeller, in a longitudinal direction at an angleto the plane of rotation of said propeller and while moving. slowly said grinding tool from the root end to the tip end of said blade or vice versa. The rotating movements of said propeller and the movements of said grin are perfectly synchronized by means of gears, the ratio between said gears determining the pitch of the propeller blade.

Inthe drawings accompanying and forming part of this specification an embodiment of myinvention isshown in which,

- Fig. 1 a front elevational view of the new' machine, Fig. '2 is a top view of a power source connected to said machine.

Like numbers denote like ures.

Referring to Fig. 1 of the drawings the new -machine comprises a table 1 adapted for rotational movement and on which the propeller 42 parts in all the figto be worked on is mounted. A grinding wheel 32 bears against the face of the blade 43, of the propeller 42 mounted on said table I. Said wheel 32 is adapted for longitudinal movements, these movements being controlled by Screw thread 8. The mo ements of table I and screw thread 8 are perfectly synchronized by a series of gears 2, 3, 4|, 4, 5, 6 and l. Gears2, 3, 4, 5 and 6 are travel gears and gears 4| and l are magnifying'gears. The ratio between table gear 2 and screw thread 3, which is determined by the ratio between gear 2 and gear 4|, and the ratio between gear 4 and gear I, determines the pitch of the propeller ding tool blade. A table of gear ratios for blades of difierent pitches will be given hereinafter.

Said screw-thread 8 engages with a threaded block 9 rigidly attached to a hollow block member ll. Said member I I is adapted for vertical. movements on stationary column l2 through the medium of roller bearings (not shown for purposes of simplicity) provided at the top and bottom of each of the sides of said member ll.

' Support arm l3" extends from said member ll .over said table I and said arm I3 is adjustable through joint 15 and set screws 33, 34 in support plate 35 and, when desired, is set at an angle to the plane of said table I. Said support plate 35 is attached to member I l and has the cable 36 of the counter balance 31 attached thereto, said cable 36 being led over pulleys 38, 39 attached to said column l2.

Screw-thread it extends along the length of said arm l3, as shown, and said screw-thread I6 is driven by motor I! through a series of gears I9, 20, 2|, 22, 23, 24 and Shaft 25, as shown.

Said shaft 25 is provided with universal joints 26 to permita change in position of said shaft 25 when said arm I3 is moved from its horizontal position. Carrier 2'! slides along said arm l3 actuated by screw-thread l6, engaging with a screw-block 52 in said carrier 21. Angie arm 28 is attached to said carrier 2! and is adapted for vertical manual adjustment thereon by screw 53: Motor support part 29 is attached to angle arm 28 and is adapted for horizontal adjustment thereon by screw-thread 30. Motor 3|, driving inding wheel 32, is rigidly attached to said Support part 29.

In Fig. 2 a driving mechanism 'for the machine is shown in which arm 46 on gear 3 is moved through an arc first in one direction and then in v the reverse directionvby the revolution of disc 48 about the center 49 thereof, the end 41 of shaft 40 being oiT-set from said center 49 and the end 50 of said shaft 40 being engaged withsaid arm 46 of gear 3. The magnitude of the are through which table I and the arm 46 travels is governed by the distance of the end 50 from the center 5| of said gear 3, this distance may be changed as desired by means of screw-thread 55 in said am 46 engaging with said end 50. The disc 48 is driven in a continuous rotary movement by means of a motor and a worm wheel reduction (not shown for purposes of simplicity).

The operation of the device is as follows:--

A propeller 42 is rigidly mounted on table I the center of said propeller 42 coinciding with the center of said table 1, as shown in Fig. 1. The.

blade 43 of said propeller 42 on which a helicoid is to be generated is situated at one end of its/ arc of rotation. Said grinding wheel 32 is then brought into position against the face of said blade 43, at the root end thereof, and at the generatrix of the helicoid It will be obvious to forward edge of said blade 43, by suitably adjusting parts 28 and 29. Power is applied to the driving mecha ism of, shaft 40, described heretofore which r tates said table 1' and the propeller 42 mountedthereon through an arc, first in one direction and then in the reverse direction, and which moves said grinding wheel 32 in a longitudinal direction in the same manner, both movements being simultaneous and synchronized, by means of the mechanism described heretofore and thus the grinding wheel 32 is moved across the face of said blade 43 from the forward edge to the back edge thereof and vice versa on successive movements of said table I and said wheel 32. Simultaneously with the movement of shaft 40 current is applied to said motors ll and 3| and grinding wheel 32 is started into operation and travels slowly from the root end to the tip end of said blade the said grinding wheel 32 overlapping part of its path on each successive longitudinal movement thereof. The combined movements of these steps generates a true helicoid on the blade of the propeller subjected to the process. The succeeding blade of the propeller is then brought into the same position on said table I as that occupied by the original blade and grinding wheel 32 is returned to its original position at the root end of the blade of the propeller by reversing motor ii. The operation is then started anew and is repeated until a true helicoid is generated on each of the propeller blades in turn.

The ratio between table gear 2 and screwthread 8 which depends upon the ratio between table gear 2 and gear 4| and the ratio between gear Qand gear 1 determines the pitch of the propeller blade. I have demonstrated that these relationships should be in the following order for various pitches:-

Ratio between gBfiIS Pitch 4-7 2-41 located between 4and7 The arm l3 1s not, however, parallel to the those skilled in the art that the point of contact between the grindingwheel 32 and the blade 43 of the propeller 42 is at a different part of said wheel 32 as it travels from the root end to thetip end of said blade 43. For example, if the distance from the root end to the tip end of said blade is divided into three equal parts a line connecting the contact point of said wheel 32 and the center of said wheel 32 is, for example, at an angle of 45 from the vertical at the first division line from the root end of the blade; at an angle of 35 at the second dividing line, and at an angle of 25 at the third dividing line. It will be understood, of course, that these angles aretaken purely arbitrary and vary with blades of different pitches. The arm l3 must thus be at such angle with respect'to the generatrix that the contact point on said wheel 32 follows the generatrix exactly when saidwheel 32 travels from the root end to the tip end of the propeller blade, if the longitudinal motion thereof is eliminated.

The practical method of determining the angle of inclination of arm i3 is by tracing the generatrix on the blade of the propeller and adjusting said arm l3 at such angle that the contact point between the surface of the blade and wheel 32 follows exactly the generatrix. Arm i3 is set at the desired angle by adjusting set screws 33 and 34 to move said arm IS on joint l5, universal joints 26 being provided to permit the movement of shaft 25 from its normal position.

Gear shift handle 4| is provided to disengage gear 23 with gear 23 and to engage ear 13 with gear 22 to increase the speed of travel of grinding wheel 32 from the root end to the tip end of the propeller blade when that is desired.

From what has been said above it will be apparent that the above described process and machine is adaptable for fashioning the pattern of apropeller or the like.

While I have shown and described and-have pointed out in the annexed claims certain novel.

process and in the operation and in the form I and details of the apparatus involved and in its use and operation may be made by thoseskilled in the art without departure from the broad spirit and scope of the invention.

I claim as my invention: 7

1. A machine for generating helicoids on propeller blades comprising a work support on which the hub of said propeller is axially mounted, means for rotating said work support and therewith the blade being worked upon first in one direction and then in the reverse direction through an arc of a circle, a guide-support mounted on a frame support offset from the axis of rotation of said work support, a grinding wheel mounted on said guide-support, means for driving said grinding wheel, means for oscillating said frame support and therewith said grinding wheel in a direction at an angle to the plane of rotation of saidwork support, the rotating movements of said work support and the oscillating movements of saidv wheel being synchronized by means of gears, the surface of said blade and said wheel being in operative contact on each successive movement thereof, means to move said wheel along said guide-support from the root .end to the tip endof said blade, said wheel overlapping part of its path on "lid surface on each successive movement thereof, said guide-support being at an angle to the generatrix ofthe helicoid being generated on the surface of said blade whereby the contact point between said wheel and said surface is maintained coincident with said generatrix.

2. A machine for generating helicoids comprising means for rotating the surface on which the helicoid is to be generated first in one direction and then in the'reverse direction through an arc of a circle, means offset from the axis of rotation of said surface to oscillate a rotary cutting tool against said surface in a direction at an angle to the plane of rotation of said surface, said surface and said cutting tool being in operative contact on each successive movement thereof, means to synchronize the movements of said tool and said surface, means to drive said cutting tool and means mounted on said oifset oscillating means to move and guide said tool along the length of the generatrix of the helicoid, said guide means being at an ,angle to said generatrix.

3. A machine for generating helicoids comprising means for rotating the surface onwhich the helicoid is to be generated first in one direction and then in the reverse direction through an arc of a circle, means offset from the axis of rotation of said surface to oscillate a rotary cutting tool against said surface in a direction at an angle to the plane of rotation of said surface, said surface and said cutting tool being in operative contact on each successive movement thereof, means to synchronize the movements of said tool and said surface, means to drive said cutting tool and means mounted on said ofiset oscillating means to guide said tool along the length of the generatrix of the helicoid, said guide means being at an angle to said generatrix whereby the contact between said tool and said surface is maintained coincident with said generatrix.

4. A machine for generating helicoids comprising means for rotating the surface on which i the helicoid is to be generated first inone direction and then in the reverse direction through an arc of a circle, means offset from the axis of rotation of said surface to oscillate a rotary cut-' ting tool against said surface in a direction at an angle to the plane of rotation of said surface, said surface and said cutting tool being in operative contact on each successive movement thereof, means to synchronize the movements of said tool and said surface, the working part of said tool being of lesser width than the helicoid being generated on said surface, means to drive said rotary tool and means mounted on said ofise't oscillating means to guide said tool along the length of the generatrix of the helicoid, said guide means being at an angle to said generatrix whereby the contact between said tool and said surface is maintained coincident with said generatrix.

JOHN FERGUSON. 

